Extraction method of fishing effort and net position in stow net vessels based on vessel monitoring system data

Abstract:

Fishing effort is one of the important parameters in the field of fishery resource management and assessment. Traditional fishing effort calculation methods cannot satisfy the needs of real-time, large-scale and rapid statistics. This study takes the stow net vessels operating offshore in China as the research object, and adopts the BP (Back Propagation) neural network model. Through the state judgment of the latitude and longitude coordinates, speed, heading and other information of the five consecutive voyages acquired by the Beidou Fishing Vessel Monitoring System in 2016 and 2017 of Zhangwangchuan 155, the net position coordinates of each voyage operation were obtained. By screening the position and time of the fishing net through the threshold and calculating the fishing time, the fishing effort can be calculated by the fishing net opening area multiplied the fishing time. Combined with the judgment results of BP neural network and threshold analysis, the accuracy of obtaining the network position data is 82%. The cumulative fishing time of the four voyages was 3 562.62 h, and the accumulated fishing effort was 712 524 (m²·h). The state judgment, net position identification, extraction of release time, and calculation method of fishing effort designed by this paper may provide new research ideas for the analysis of the net operation and the quantification of its fishing intensity.